I have a 2004 Ram 1500 4x4 5.7 hemi, 176,000 on truck 12,000 on engine. Tune up done with all OEM parts when engine was replaced (done at Dodge dealer). I have a code for misfire on #7 and open circuit fuel injector on #5. I have done the following, tested spark on all plugs, compression test, leak down test, and noid light test. I am unsure on what I should check next. The truck runs rough at idle and at lower speed load, if I drop a gear and give more throtle it smooths out and runs great. It did this last time also but that time it faild all tests for compresion and leak down on #7 (this is why it has the newer engine). Any ideas please help, I cant afford to throw money at the problem to do trial and error. Thank you!

By the way, new to the forum so, Hi y'all!

 

I just fixed my 4.7 that had a misfire on #2 cyl. It ended up being the coil pack. Check the connections at the injector to make sure it's not loose or disconnected.

 

Both the coil pack and connections are good, I have great spark from both points on the coil pack. Thank you for the reply! Any other ideas?

 

Welcome to Dodge Forum!



So this is a salvage yard engine?

 

This was a complete reman/rebuild. They started from bare block and put everything new into it to make it a long block.

 

OK, gotcha. I there a reason you haven't gone back to them to get them to fix it? Or was this a while ago?


Anyway, you need to go after the #5 Injector code FIRST. Misfires are subjective, but a circuit code is not, so that's why first. Keep in mind that a malfunctioning cylinder can affect the whole bank (1357) and sometimes both banks. The #7 may be a result of the #5 in other words.


Take an Ohm meter and measure across #5 injector and compare it with a couple more injectors.

 

Now I just have to find my DVOM in my garage that my wife took over for a garage sale! LOL Thank you for a new place to start looking! The engine was done almost 3 years ago, just a little past waranty! :-)

 

I got a 12.4 on #5 and the others that I checked ranged from 12.0-12.3

 

That is within tolerance.

Might be time to pull the valve cover and check the valve springs.....

What did you compression test come back as?

 

150psi and held (dropped maybe 2-3psi) for 20 minutes (while I ate lunch). It was within the same tolerance as the other cylinders (between 140-160 aprox). There was no pinging in the valve train and it does have the upgraded springs installed already. I am going to take it to the dealer for diagnostics, it could be something as simple as a cracked or corroded wire that I would not be able to track down. I cant figgure it out!

Thank you all for the info and insight!